Digitalized coincidence correction method and circuitry for particle analysis apparatus

ABSTRACT

So as to generate a correct count of particles from apparatus which progressively loses individual counting pulses primarily due to the physical coincidence of two particles in the detecting transducer of the apparatus, the subject method enables digitalized addends to be progressively added to the augend formed by the detected count so as to yield, as a continuously forming sum, a corrected count which closely approximates the true particle count. The subject circuitry includes a series of decade counters which receive the detected, augend, pulses and, at progressive count levels, such as increments of one thousand, enable, and/or trigger a selected one of a plurality of correction establishing circuits, to deliver one or more addend related signals to a selected one of the decade counters. Depending upon the number of such related signals and the numeric rank of the receiving decade counter, a predetermined addend is supplied. This trigger and feedback relationship increases the increments of addend as the detected count increases.

iilnited States atent Inventors Jacques A. lPontigny Montmorency; Claude J. Colllineau, Epinay/Seine, both 01' France Appl. No. 633,646

Filed June 16, 1969 Patented Dec. 7, 1971 Assignee (Ioulter Electronics, llnc. Hialeah, Fla.

Priorities June 19, 1968 France 155649;

June 19, 1968, France, No. 155650 lDllG WALHZED COINCHDENCE CORRECTION METHOD AND ClRCUlTRY lFOlR PAlli'llllClLlE [56] References Cited UNITED STATES PATENTS 3,361,897 l/l968 Rush 235/1513 3,439,267 4/1969 Coulter et a1. 235/92 UX Primary Examiner-Malcolm A. Morrison Assistant Examiner-R. Stephen Dildine, Jr. Attorney--Silverman & Cass ABSTRACT: So as to generate a correct count of particles from apparatus which progressively loses individual counting pulses primarily due to the physical coincidence of two particles in the detecting transducer of the apparatus, the subject method enables digitalized addends to be progressively added to the augend formed by the detected count so as to yield, as a continuously forming sum, a corrected count which closely approximates the true particle count. The subject circuitry includes a series of decade counters which receive the detected, augend, pulses and, at progressive count levels, such as increments of one thousand, enable, and/or trigger a selected one of a plurality of correction establishing circuits, to deliver one or more addend related signals to a selected one of the decade counters. Depending upon the number of such related signals and the numeric rank of the receiving decade counter, a predetermined addend is supplied. This trigger and feedback relationship increases the increments of addend as the detected count increases.

UIUII i1 31 ii/ PATENTED DEC 7 |97| SHEET 1 BF 5 Inventors JACQUES A. PONTIGNY CLAUDE JEAN COLLINEAU iii;

mmmdm OOQO.

mmm CO- mm hm ATTYS PATENTEDUEB H97: 3.626164 SHEET 2 OF 5 IOI lnveniors JACQUES A. PONTIGNY BY CLAUDE JEAN COLLINEAU MWWdwu ATT YS.

TOTAL CORRECTION PATENTEUUEC 7191: 3 526,154

SHEET 3 BF 5 1 l I I I DETECTED PULSES vemo s CORRECTED COUNT JACQUES A. PONTIGNY CLAUDE JEAN COLLINEAU ATTYS.

PATENTEU DEC 7 I971 SHEET M 0? 5 w E MGM L mmL m m N A SE E U U E D U A A L C Y B ATTYS.

PATEN'IEU mm: 7 :97:

SHEET 5 BF 5 Inventors JACQUES A. PONTIGNY BY CLAUDE JEAN COLLINEAU ATTYS.

BACKGROUND OF THE INVENTION This invention is directed to a method and counting circuitry which provide a statistic correction to a detected train of count pulses, such that effective random loss of the phenomena being counted does not induce ultimate counting error.

Now well known in the art of electronic particle counting and analyzing is apparatus marketed under the trademark Coulter Counter. Such apparatus and portions thereof are disclosed in several US. Pats, for example, Nos. 2, 656,508; 2,985,830; and 3,259,842. A significantly important portion of such apparatus is the minute scanning aperture or scanning ambit relative to or through which pass and are detected single particles at a rate often well in excess of 1,000 per second. Because of the physical parameters of the scanning aperture, particles, rate of flow, etc. there frequently results the coincidence of two particles in the scanning ambit. As a result, there is effectively scanned and detected only one particle, not two.

Although such coincidence is random in time, it follows a statistically ascertainable course from which curves, tables, and formulas are obtainable. A relatively simple one of such formulas is:

n'=k(n*/1000) in which n the total number of coincidences, i.e., the required addend;

k a constant which relates primarily to the physical parameters of the scanning elements of the apertures and the average particle size; and

n the detected number of particles, the augend. Ac-

cordingly, the desired or corrected count N will equal the sum of n+n.

Heretofore, the operator ofa Counter Counter" would obtain the augend count by analysis of a suspension of particles and then would refer to a coincidence correction chart which presented the proper correction or addend for a very large selection of augends. The sum thereof would then be the corrected count which the operator would record.

Although the use of charts provides an accurate result, it is both time'consuming and prohibits the fully automatic recording and processing of the corrected counts. Also, of course, the accumulating count during analysis is uncorrected.

The use of analog, nonlinear meters and/or elements in the output state of a Counter Counter" has also been accomplished with limited success; however, in many used a direct reading digitalized output is greatly to be preferred.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of this invention to provide method and circuitry which provide a digitalized, direct reading corrected output for a counting apparatus that requires a continuously applied correction factor.

Another object of the invention is to provide automatic, digitalized coincidence correction circuitry for particle analysis apparatus.

A further object of the invention is to provide digitalized coincidence correction circuitry which operates in a feedback mode to incrementally supply addends to the particle count as it is being accumulated.

To achieve the above and other objects and overcome the deficiencies in the prior art, the invention provides method and circuitry exemplified by a plurality of decade counters serially coupled to the output of the particle scanner. Certain of the decade counters provide, at predetermined count levels. enabling and triggering signals to correction establishing circuits of a correction pulse generator, which in turn generate one or more correction pulses that are fed back to at least one of the decade counters. Because of the interconnection of the circuitry elements, the incremental corrections progressively cause the sum or corrected count to follow a true count curve.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a particle analysis apparatus inclu'ding the present invention;

FIG. 2 is a diagram of the decade counter and correction pulse generator portions of the invention;

FIG. 3 is a graph showing a theoretical statistic correction curve and curves and other indicia related to the method and operation of the invention;

FIG. 4 is a schematic diagram of the combination of the delay circuit and one of the correction establishing circuits in a preferred embodiment of the correction pulse generator of the invention;

FIG. 5 is a chart showing waveforms related to the schematic in FIG. 4; and

FIG. 6 is a schematic diagram of a preferred form of the correction pulse generator of the embodied invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Although practice of this invention is not limited to its use with a Coulter Counter, such will be the described embodiment, particularly with reference to FIG. 1. Such an apparatus comprises a detector 1, including a beaker 2 filled with a sample liquid containing the suspension of particles to be counted. A glass tube 3 of substantially smaller diameter extends into the beaker, is closed at its lower end, and is connected to a source of vacuum (not shown) and to a siphon manometer 4. The lower end of the tube 3 has an aperture 5 in its lateral wall. The aperture is of microscopic size and, for example, is in a sapphire member fixed permanently in said well.

The aperture tube 3 an all the other accessories are filled with a compatible fluid or additional amounts of the sample liquid. Two electrodes 6 and 7 are provided on each side of the aperture 5 and are connected. to conductors 8 and 9, which constitute the output terminals of the detector.

The manometer 41 is employed for causing a given amount of the sample liquid to pass through the aperture. It comprises a column of mercury 10 and its free end is open to the at mosphere. The column of mercury is so arranged that, in the course of its movement, it touches contacts l1 and 12 which serve respectively to start and stop the counting procedure. For this purpose, the column of mercury can be grounded.

To operate this detector, the operator opens a cock 13 leading to the source of vacuum so that the column of mercury moves into an unbalanced condition as illustrated. After closure ofthe cock 13, the column of mercury 10 tends to resume its state of balance and in doing so draws the sample liquid through the aperture 5. The column of mercury then comes in contact with the electrode Ill and an electrical potential is created across the electrodes 6 and 7 to produce a current in the liquid through the aperture. Now, in passing through the aperture, the particles in suspension modify the impedance between the two electrodes 6 and 7, so that said current is modulated and produces a series of pulses.

The conductors 8 and 9 are connected to a pulse amplifier 14 which, owing to a shaping circuit therein converts the input series of pulses into rectangular signals having a fixed width and height. The output of the amplifier 14 is connected to a decade counter array 15 comprising two transistor decades l6 and 17, each of which consists of four flip-flop circuits which are interconnected in the known manner as to afford a division by ID. The decade 17 is followed by an amplifier l8 connected to a series of three thyratron decades 19, 20 and 21.

The amplifier l8 converts the signals which issue from the decade 17, and have a width varying as a function of the mean counting frequency, into constant width pulses and amplifies them in such manner as to render them capable of acting on the thyratrons of the following decades. In a preferred embodiment, each of the latter comprises a shaping thyraton, a

series of counting thyratrons, and a series of 10 interrogation thyratrons. The counting and interrogation thyratrons are coupled in pairs through their cathodic load in such manner as to interrogate the decades, as will be explained hereinafter.

A control circuit 22 is connected to the electrodes 11 and 12 of the decoder 1 and moreover to a multivibrator 23, which produces pulses at low frequency for example at 3 Hz. The control circuit also acts on switches 24, 25 and 26 which bring associated systems into circuit at appropriate instants. For this purpose, the control circuit comprises conventional delay circuits which will not be described in detail.

The output of the multivibrator 23 is connected, through a shaping circuit 27 and the switch 24, to an interrogation lead 28 connected to the interrogation thyratrons of the decades 19, 20, and 21. The multivibrator is also connected to the inputs of a series of three amplifiers 29, 30 and 31 whose outputs are connected to a printer 22 comprising, for each digit position of the registered number, a drum or number which is individually movable step-by-step by the effect of pulses applied to its drive means. Each of the amplifiers 29, 30 and 31 includes a blocking input 33 which is connected to one of the series of interrogation thyratrons of the considered decade through conductors 34.

A correction pulse generator 35 is associated with the counter array an will be described hereinafter in considerable detail an will other circuit portions illustrated in H6. 1, but not yet mentioned.

A source of power 36 is provided which suitably feeds each circuit of the apparatus through conductors which, in the interest of greater clarity, have not been shown.

FIG, 2 shows the block details of correction pulse generator 35 and includes the counter array 15 of which the shaping amplifiers 14 and 18 have been omitted. This circuitry is so arranged as to introduce a statistic correction in the count effected by the decades 16, 17, 19, and 21 in such manner that corrected count is as near as possible to the theoretical count afforded by the formula given hereinbefore. Accordingly, an automatic correction is made each time the decade 19 emits a pulse, that is, for each thousandth pulse counted by the decade counter array. The correction cycle is divided into four parts having ranges respectively from 2,000 to 9,999; 10,000 to 39,999; 40,000 to 79,999; and 80,000 to 100,000. In each of these ranges, a different amount of correction is made. Thus, in the order or the ranges just mentioned, 20, l00,200 and 400 addend counts are added to the registered, augend, count each time the decade 19 of the thousands produces an output pulse. It should be mentioned that no correction is made below the number 2,000 in respect of the described example.

The correction pulse generator 35 comprises four correction circuits each consisting of a correction pulse establishing circuit and a control circuit, these correction circuits serving respectively for the corrections of 20, 100,200 and 400 per L000 pulses counted. For this purpose, a lead 37 takes a signal from the output 38 ofthe decade 19 and transmits it to a delay circuit 39. The output 40 of this delay circuit is connected to four correction establishing circuits 41 to 44 through input leads 45 to 48. The pulses issuing from the decade 19 are also applied to the control circuit 49 through a lead 50 connected to the lead 37. The pulses issuing from the decade 20 and arriving at a terminal 51 are simultaneously applied though a lead 52 to the input leads 53 to 55 of control circuits 56 to 58, respectively. Further, a lead 59, connected to the decade 21, transmits a pulse to a triggering input of the control circuit 57; whereas, a lead 60, also connected to the decade 21, transmits a pulse to a triggering input of the control circuit 58 when the decade counter reaches the numbers 30,000 and 70,000 respectively.

An output from the correction establishing circuit 41 is connected to an input of the tens decade 17 through a lead 61. This circuit 41 transmits two pulses to this decade 17, i.e. makes a correction of 20 for each thousandth pulse registered by the decade counter array.

The outputs from the correction establishing circuits 42 to 44, respectively send, for each pulse received at their inputs 46 to 48, one, two or four correction pulses to the input of the decade 19 and advances the latter one, two, or four ranks of each respectively. This is carried out through diodes 62 and a lead 63 and initiating elements to be described in connection with FIG. 4.

The correction pulse generator 35 is started and stopped by a starting and resetting circuit 64 which receives signals from the control circuit 22 in HO. 1 through leads 65 and 66. Finally, the circuits described hereinbefore are fed from an input terminal 67 connected to the power source 36.

it should be mentioned that the embodiment described preferably employs as triggering elements cold-cathode thyratrons which have been found to be particularly suitable for the purpose, however, it is obvious that these elements can be replaced by other electronic triggering components, such as for example, vacuum tubes or semiconductors, providing. that the appropriate technological adaptions are made.

Turning next to FIG. 3, there is shown a graph having a plurality of difierent sets of indicia along its exponentially spaced abscissa and ordinate divisions. Extending upwardly along the ordinate of the graph is the cumulative value of addend or correction applied to the decade counter array labeled Total Correction." Extending upwardly along the right margin of the graph are the four previously mentioned ranges which commence at 2,000; 10,000; 40,000; and 80,000 corrected counts then stored in the decade counter array.

The Detected Pulses or augend is marked along the abscissa with indicia commencing at 700 and terminating past 80,000. Directly therebelow, on the same scale, but with necessarily earlier points of intersection of the same count values, is the Corrected Count" index.

A theoretical or statistic correction curve 68 is plotted to show to the progressively required total correction with reference to the detected or uncorrected number of pulses which would be emitted from the amplifier 14 in H0. 1. Thus, at any point on the curve 68 there is a corresponding total amount of required correction and this data could be tabulated to provide a correction table of the type earlier mentioned as a form of the prior art in which manual count correction is possible,

However, in order to render the correcting method and apparatus automatic, an automatic correction curve 69 is first established in the form of steps which is as near possible to the statistic correction curve, taking into account a certain previously imposed accuracy. The limits of this accuracy are indicated by a pair of curves marked +l percent and ---1 percent designating their value limits. Of course, it is possible to be more or less exacting in the accuracy by providing an automatic curve having a greater or smaller number of steps and consequently a greater or smaller complication of the electronic circuits of the apparatus.

Before discussing the schematic details of FIGS. 4-6, the overall operation of the invention will be discussed from the point in time that the 1,000th detected pulse has been received by the decade count array 15. At such time, the decade 19 emits at its output 38 a triggering signal to the control circuit 49, by way of the leads 37 and 50, which enables the correction establishing circuit 41, but does not elicit therefrom any correction signals. Upon receipt of the 2,000 detected pulse, the decade 19 again produces a trigger signal which, by way of the delay circuit 39 and the leads 40 an 45, is coupled to the correction circuit 41 and causes it to produce two correction pulses. The latter are applied to the input of the decade 17 through the lead 61. The decade 17 thus advances two ranks and therefore adds 20 to the registered count, the indicated total or corrected count then being 2,020 pulses. Thereafter, each time the decade 19 emits an output signal, the correction circuit 41 sends two pulses to the decade 17 so as to add 20 to the registered count. Thus, when the counter indicates the number 10,000 the detector has delivered only 9,840 pulses.

At the count of 10,000, the decade 20 emits a pulse at the output 51, the control circuit 56 is actuated through the leads 52 and 53 to enable the circuit 42, while the pulse establishing circuit 41 is simultaneously inhibited (by circuit means subsequently to be discussed). When once again the decade 19 emits a pulse, the pulse establishing circuit 42 is triggered by way of the delay circuit 39 and the input lead 46 and the circuit sends one pulse to the input of the decade 19 through the lead 63 so as to advance it one rank and cause it to make a correction of 100. Each time, the decade 19 thereafter emits a pulse a correction of 100 is made by the pulse establishing circuit 42.

When the decade 21 attains the number 30,000, it sends a pulse on the lead 59 to the control circuit 57 so as to enable it. Upon the arrival of the following output signal, at the terminal 51 of the decade 20 representing the number 40,000, the control circuit 57 is triggered by way of the leads 52 and 54 and enables the pulse establishing circuit 43 and also inhibits the pulse establishing circuit 42. Upon the arrival of the following pulse at the output of the decade 19, number 41,000, the pulse establishing circuit 43 sends two correction pulses to the input of the decade 19 so as to provide an addend of 200. Thereafter, each time the decade 19 emits a pulse, a correction of 200 is made in the count of the counter array 15. Thus, when the latter indicates the corrected count of 40,000, only 37,100 pulses have been delivered by the detector 1.

When the decade 21 attains the corrected count of 70,000, a pulse is sent to the control circuit 58 so as to enable it through the lead 60. Thereafter, as soon as the decade 20 emits the following output pulse, number 80,000 on the leads 52 and 55, the control circuit 58 enables the pulse establishing circuit 44 and inhibits the pulse establishing circuit 43. The following pulse emitted by the decade 19, number 8|,O00, produces for pulses at the output of the pulse-establishing circuit 44, these pulses being sent to the decade 19 and providing an addend of 400. This is thereafter repeated until the counter array 15 is completely full.

It will be observed that the counting could very well stop before the counter 15 is full, the number finally registered depending on the number of particles contained in the measured volume of the sample liquid. Moreover, the counting is stopped by the column of mercury when it touches the contact 12. At that time, the given volume of the liquid sample has passed through the measuring aperture 5. The stopping of the counting by means of the column of mercury 10 also triggers the multivibrator 23 through the control circuit 22, and the latter closes the switches 24 to 26 at the appropriate moments,

The multivibrator 23 transmits the interrogation pulses to the shaping circuit 27 and these pulses are thenceforth applied to the interrogation thyratrons of the decades 19 to 21 so as to interrogate them. At the same time, the multivibrator 23 transmits pulses to the amplifiers 29 to 31 whichare connected to the printer mechanisms corresponding to the hundreds, thousands and ten thousands through the switches 26.

The interrogation pulses have two particular purposes. They cause the drums of the registering mechanisms of the printer to advance simultaneously step by step, and they interrogate the interrogation thyratrons of the decades 19 to 21. As soon as, in the interrogation series of the decade concerned, the interrogation thyratron corresponding to the energized counting thyratron is reached, a blocking pulse is sent to the corresponding amplifier through the lead 34 so that the amplifier is blocked. The drum of the printer 32 then stops at the number represented by the interrogation thyratron that was energized.

In order to further facilitate understanding of the invention and its operation, a preferred embodiment of one of the correction pulse establishing circuits will be described with reference to FIG. 4, this circuit being similar to each of the circuits 41-44 and associated with a delay circuit similar to the circuit 39.

As shown in FIG. 4, two thyratrons 70 and 71 have their anodes connected to a +200 v. source, for example, through anode resistors 72 and 73. The cathode of the thyratron 70 is grounded through an RC circuit comprising a resistor 74 and a capacitor 75. The grid of the thyratron 70 receives control pulses through a capacitor 76 and it is polarized by a +100 v. source, for example, through a resistor 77. The cathode of the 1 thyratron 70 is also connected to a coupling capacitor 78 which is connected to the grid of the thyratron 71. This grid is polarized at the voltage of H00 v. through a resistor 79. The cathode of the thyratron 71 is grounded through an RC circuit consisting of a resistor and a capacitor 81 and is connected to the output of the circuitry through a diode 82. Note that the RC time constant of the resistor 74 and the capacitor 75 is much greater than that of the resistor 80 and capacitor 81.

The operation of this circuitry is as follows with reference to FIG. 5. An input or count pulse is applied to the capacitor 76 and causes, after a certain inherent delay I, the ionization of the thyratron 70 which, being conductive, charges the capacitor 75. This charging continues until the voltage at the terminals of the capacitor has such value that it lowers the anode-cathode voltage of the thyratron below the ionization value. The thyratron thus becomes. nonconductive. The time constant of the RC circuit 74 and 75 is so calculated as to produce the conduction curve 86 in which a threshold voltage 87 defines the conduction range of the thyratron 70.

The operation of the thyratron 71 is identical to that of the thyratron 70. Thus, a pulse applied to the grid of the thyratron 71 triggers the latter and charges the capacitor 81 until the voltage at its terminals reaches such value that the thyratron ceases to conduct. As mentioned before, the charging time of the capacitor 75 is much longer than that necessary for charging the capacitor 81. Consequently, during the time which elapses between the thyratron conduction range of the curve 86, during which the capacitor 78 is also charged, the latter periodically transmitting a part of its energy to the grid of the thyratron 71 by way of a pulse train 88, the thyratron 71 is periodically conductive and periodically charges the capacitor 81. The number of times that the capacitor 81 can be charged and discharged therefore in particular depends on the capacity of the capacitor 78.

For a resistor 74 of 560 ohms, a capacitor 75 of 47 microfarads, a resistor 80 of l megohm and a capacitor 81 of 0.22 microfarads, a value of 1.5 microfarads must be chosen for the capacitor 78 to obtain one pulse, 2.7 microfarads to obtain two pulses and 5.l microfarads to obtain four pulses. the latter as in the pulse train 89, per input pulse 85.

In the embodied apparatus, there are employed only the single delay circuit 39 such as that described hereinbefore, and the four correction pulse establishing circuits 41-44, each of which comprises an input capacitor, such as the capacitor 78 having the appropriate value. A schematic thereof is shown in FIG. 6. Thus, the output lead 40, which is connected to the junction point of the capacitors 75 and 78 in FIG. 4 is similarly connected to each of the correction pulse establishing circuits 41-44 through their respective capacitors 78 in FIG. 6.

As previously mentioned, each of these pulse establishing circuits is associated with a respective control circuit 49, and 56-58, comprising a thyratron 90 which is capable of polarizing, when rendered conductive, the grid of the thyratron of the associated pulse establishing circuit. This is effected through the respective leads 91-94 also shown in FIG. 2. The thyratrons of the control circuits can be polarized by a polarizing voltage through the lead 52 to the input leads 5355. Thus, the thyratrons are polarized only upon the counter array 15 being filled up to 10,000. On the other hand, the thyratron of the control circuit 49 is polarized as soon as the operator has started the apparatus and ionized the thyratron 95 of the circuit 64 by means of the terminal 65.

The thyratrons of the apparatus are arranged in two main groups A and B as to their anode source. For this purpose, the power source 36 comprises two distinct parts each of which consists of a common anode resistor 96 for the considered group, this resistor being in series with a diode 97 between two supply lines 98 and 99 brought respectively to potentials of +400 and +200 v. The terminals A and B are at the junctions of the respective resistors and diodes and are connected to the anode terminals of the thyratrons of the respective groups, these terminals having the corresponding letter references in FIG. 6. Owing to this anode coupling of the two groups of thyratrons, only a single thyratron per group can be triggered; and the thyratron, which is triggered at a given moment by means of a voltage applied to its grid, renders nonconductive the previously conductive thyratron in respect of which the anode voltage is then too weak to maintain the ionization.

The operation of the circuitry shown in FIG. 6 will now be described in detail from a starting point at which it will be assumed that none of the thyratrons of the circuitry is conductive. Starting up is achieved by the application of a pulse at the terminal 65 of the start circuit 64, its thyratron 95 being rendered conductive and the grid thereof being permanently polarized by a potential of +100 v. The current which is established in the thyratron 95 supplies a potential by way of a lead 100 to the grid of the thyratron 90 in the control circuit 49 so as to polarize it. The pulse establishing circuit 41 is then enabled to receive the thousandth pulse recorded by the counter.

At the moment the decade 19 counts the thousandth pulse, it transmits a pulse to the delay circuit 39 through the lead 37 and as the thyratron 70 is permanently polarized by a potential of+100 v. on its grid, it is rendered conductive. At the same time, the thyratron in the control circuit 49, previously polarized through the lead 100, is rendered conductive by way of the lead 50 and thus polarizes the thyratron 71 in the correction circuit 41 through the concerned lead 91.

Upon the arrival of pulse 2,000 in the counter, the decade 19 transmits a new pulse to the delay circuit 39 so that the thyratron 70 previously rendered nonconductive by its cathode capacitor 75, is rendered once more conductive, and owing to the polarization of the thyratron 71 and to the value of the capacitor 78, the latter will produce two pulses which are transmitted by the output lead 61 of the correction circuit 41 to the tens decade 17 so as to cause it to advance two ranks.

An addend value of 20 is thus added to the uncorrected count value of 2,000 and the counter jumps to the number 2020 as shown in the lower left corner of FIG. 3. This correction is thenceforth made each time the decade 19 produces an output pulse corresponding to the number 1,000, so that the arrival of the pulse 9,840 at the input 101 of the counter 15, the latter displays in fact the coincidence corrected number 10,000.

As soon as the pulse corresponding to the number 10,000 issues from the decade 20, the thyratron in the control circuit 56 is rendered conductive through the leads 52 and 53. Simultaneously, the corresponding thyratron in the control circuit 49 through is turned off owing to the common anode coupling to point A in the power source 36 as earlier explained; this operation thenceforth preventing the conduction of the thyratron in the correction circuit 41 whose polarization is eliminated. On the other hand, the grid of the thyratron in the correction circuit 42 is polarized through the associated lead 92. As soon as the decade 19 once more records the arrival of 1,000 pulses; that is, when the counter displays 11,000, it transmits the signal to the grid of the thyratron 70 in the delay circuit which renders it conductive. Then, owing to the value of the capacitor 78 in the circuit 42, only one pulse is produced by the thyratron 71 therein, this pulse being transmitted to the input of the decade 19 through the concerned diode 62 and the lead 63. As the decade 19 advances one rank, a correction value of 100 is added to the number displayed by the counter 15, which consequently displays the number 1 1,100. At this moment, the detector has transmitted to the counter only 10,840 pulses. This correction of 100 appears on FIG. 3 with associated reference 102 and returns the automatic correction curve 69 from 1 percent error to very close to the theoretical correction curve 68. This correction is repeated thereafter each time the decade 19 emits an output signal until the counter displays the number 40,000. However, at the number 30,000, the decade 21 transmits a pulse through the lead 59 whichv thus polarizes the thyratron in the control circuit 57. As soon as the counter displays the number 40,000, the decade 20 renders the same thyratron conductive through the leads 52 and 54. At this moment, the counter has received at its input terminal 101 only 36,940 pulses. Owing to the common anode coupling, the thyratron in the control circuit 56 is turned off and simultaneously eliminates the polarization of the grid of the thyratron 71 in the associated correction circuit 42. The latter can no longer produce correction pulses. On the other hand, the thyratron in the control circuit 57 polarizes the grid of the thyratron in the correction circuit 43 which, upon the arrival of the following pulse at the output of the decade 19 which is, at number 41,000, becomes conductive twice, effecting the correction value of 200, two pulses being applied to the input of the decade 19. This correction of 200 is made every thousand pulses until the counter 15 displays the number 80,000. However, at that moment, the counter has received only 68,300 input pulses. Because of the correction beginning at 40,000, the automatic correction curve 69 again swings away from the ---1 percent curve toward the +1 percent curve; however, nearing the count of 80,000, the -1 percent curve is again being approached.

The arrival of the pulse 70,000 polarizes the thyratron in the control circuit 58 through the lead 60 so that when the decade 20 emits a pulse when it is once more filled by the following 10,000 pulses, that thyratron is turned on and the thyratron in the prior control circuit 57 is turned off, which renders the thyratron in the correction circuit 43 inoperative. On the other hand, the thyratron in the correction circuit 44 then is able to produce pulses. Consequently, upon the arrival of the pulse 81,000, the decade 19 excites the thyratron 70 in the delay circuit 39 so as to produce four pulses in the correction circuit 44 owing to the value of the capacitor 78. These pulses are applied to the decade 19 through the considered diode 62 and the lead 63. The decade 19 then advances four ranks so as to make a correction of 400. The display of the counter 15 is thereafter corrected in this way every thousand pulses until the total filling of the counter. 1f the apparatus is not wholly stopped by elimination of the source voltages on the lines 98 and 99, the thyratron in the circuit 58 remains energized until the arrival of the following starting pulse at the terminal 65. The latter, in rendering the thyratron 95 conductive, turns of any one of the thyratrons which was the last to remain energized.

It should be mentioned that the system described hereinabove represents one of many possible embodiments of the correction pulse generator 35. Further, the numerical values of the components and the numerical examples illustrating the operation of the apparatus have been given merely for purposes of explanation. The same is true in respect of the correction curves shown in FIG. 3, since they depend both upon the uncorrected error produced by the detecting apparatus and the degree of accuracy desired.

What is desired to be protected by United States Letters Patent is:

We claim:

1. A method for progressively and automatically correcting the digitalized accumulation of counting data which normally is subject to random error, comprising the steps of:

receiving in a cumulative and digitalized mode the counting data as an augend, detecting in a cumulative and digitalized mode the value of the augend relative to a succession of addend corrections and instances of correction, such instances of correction being correlated to a predetermined set of augend values,

determining the succession of addend corrections for each value in the set of augend values,

generating the correlated addend at each instance of correction, and

applying to the augend each addend as it is generated, such that the augend cumulatively is the sum of the counting data and the addends.

2. A method according to claim 1 further comprising the step of relating the amount of addend, for said generating sand applying steps, to the then detected value of the augend.

3. A method according to claim 2 further comprising the step of enabling said generating of at least some of the addends at a prior instant related to the detecting of certain augend values.

4. A method according to claim 2 further comprising repeating said generating at fixed values of the augend which are digitally spaced primarily equally from one another.

5. A method according to claim 1 further comprising the step of delaying in a predetermined mode said generating relative to said detecting for an interval based upon the receipt of a fixed increment of augend.

6. A method according to claim 1 further comprising creating by said generating different individual amounts of addend, depending upon the then received value of the augend.

7. A method according to claim 6 and further comprising producing by said generating, for said applying, at least one pulsed response, each such pulsed response being a fraction of the addend thereby applied.

8. A method according to claim 6 further comprising creating by said generating addends which are multiples of one another depending upon the values of the augend.

9. A method according to claim 1 further comprising the step of correlating the addend of each correction individually and cumulatively with a theoretical statistic correction curve.

10. A method according to claim 1 and accomplishing said receiving and detecting by arranging in digital order a plurality of count retaining stages and directing said applying, at said instances of correction, to a particular one of the ordered stages depending upon the amount of addend and the value ofthe augend.

11. A method according to claim 10 further comprising the step of obtaining from at least some of the ordered stages, as a representation of the results of the receiving and applying steps, the corrected count they are retaining.

12. A method according to claim 11 further comprising interrogating sequentially each of the stages for the count it is retaining, during said obtaining.

13. A method according to claim 1 further comprising the step of initiating the counting data in an analyzer of particles.

M. A method according to claim 13 further comprising the steps of moving a fluid suspension of particles for purposes of said initiating, and

regulating said generating and applying with reference to said moving,

15. A method according to claim 14 further comprising sensing individual particles in suspension as they pass with reference to a scanning zone, for purposes of said initiatmg,

the random error being caused by the physical coincidence of particles in the scanning zone.

16. Apparatus for progressively and automatically correcting the digitalized accumulation of counting data which normally is subject to random error, comprising:

means for receiving in a cumulative and digitalized mode the counting data as an augend, means coupled with said receiving means for detecting in a cumulative and digitalized mode the value of the augend relative to a succession of addend corrections and instances of correction, such instances of correction being correlated to a predetermined set of augend values,

means for determining the succession of addend corrections for each value in the set of augend values,

means responsive to at least said determining means for generating the correlated addend at each instance of correction, and means for applying to the receiving means each addend as it is generated, such that the augeznd cumulatively is the sum of the counting data and the addends. 17. Apparatus according to claim 16 further comprising control means coupled to said generating means for relating the amount of addend next to be generated to the then detected value of the augend. 18. Apparatus according to claim 17 further comprising means responsive to at least said receiving means for enabling said generating means, for at least some of the addends, at a prior instant related to the detecting of certain augend values. 19. Apparatus according to claim 17 wherein said detecting and control means, in combination, form means for triggering said generating means at fixed values of the augend which are digitally spaced primarily equally from one another. 20. Apparatus according to claim 17 wherein said detecting and control means are arranged to coact to correlate the addend of each correction individually and cumulatively with a theoretical statistic correction curve. 21. Apparatus according to claim 16 further comprising means interposed between said detecting and generating means for delaying in a predetermined mode the operation of said generating means for an interval based upon the receipt by said receiving means of a fixed increment of augend. 22. Apparatus according to claim 16 wherein said generating means includes means for defining different individual amounts of addend, depending upon the then received value of the augend. 23. Apparatus according to claim 22 wherein said defining means includes means for applying at least one pulsed response to the augend value, such that each pulsed response is a fraction of the addend thereby applied. 241. Apparatus according to claim 22 wherein said defining means includes means for creating addends which are multiples of one another depending upon the value of the augend. 25. Apparatus according to claim 16 wherein a plurality of digitally ordered count retaining stages comprise said receiving means and at said instances correction, said applying means is selectively coupled to a particular one of the ordered stages depending upon the amount of addend and the value of the augend. 26. Apparatus according to claim 25 further comprising means for obtaining, from at least some of the ordered stages, the corrected count they are retaining. 27. Apparatus according to claim 26 wherein said obtaining means includes means for interrogating sequentially each of the stages for the count it is retaining. 28. Apparatus according to claim 16 further comprising means for initiating the counting data in an analyzer of particles. 29. Apparatus according to claim 28 wherein said initiating means comprises means for moving a fluid suspension of particles and means for regulating said generating and applying means in response to the amount of suspension moved by said moving means. 30. Apparatus according to claim 29 wherein said initiating means further comprises means for sensing individual particles in suspension as they pass with reference to a scanning zone, the random error being caused by the physical coincidence ofparticles in the scanning zone. 31. Apparatus for automatically and progressively applying a digitalized statistic correction to a progessive accumulation of data which is transmitted in the form of a train of data pulses that is subject to random error due to the mode of transmitting such data, said error following a statistically preascertainable course, said apparatus comprising:

a counter having an input for receiving the data pulse and a plurality of outputs responsive to and designative of different data pulse count values,

a correction pulse generator having a plurality of inputs connected to said plurality of outputs and arranged to be selectively responsive to said outputs for generating correction pulses at different of said count values,

at least one feedback path coupling said correction pulse generator to said counter and arranged for progressively applying thereto correction pulses having a count value and progression occurrence so as to closely follow the preascertainable course of said error, so as to offset same.

32. Apparatus according to claim 31 wherein said correction pulse generator comprises at least one control circuit having a first group of said plurality of inputs, and

at least one pulse establishing circuit, coupled to be enabled by said control circuit, and having a second group of said plurality of inputs.

33. Apparatus according to claim 32 wherein each pulse establishing circuit is coupled to supply correction pulses to said feedback path, and

said feedback path is coupled to said counter such that each correction pulse is the equivalent to a specific multiplicity of count pulses, dependent upon the count value.

34. Apparatus according to claim 32 wherein said plurality of inputs includes a third group coupled to specific ones of said control circuits and arranged to enable them at different specific count values.

35. Apparatus according to claim 32 wherein a plurality of coupled pairs, each having one of said control circuits and one of said pulse-establishing circuits, is provided,

each said circuit pair has one of said first and second groups of inputs, and

each said circuit pair is responsive to a selectively different range of count values.

36. Apparatus according to claim 35 wherein circuitry means intercouples said circuit pairs in such manner that only one pair is capable of responding to the counter outputs at any one time, and

such capability correlates to the selectively different range of each said circuit pair.

37. Apparatus according to claim 36 wherein a first power source, which is arranged to have enough power to operate only one of said control circuits at any one time, is intercoupled to said control circuits and comprises said circuitry means, and

said first group of inputs are selectively connected to the control circuits to determine their sequence of operation.

38. Apparatus according to claim 32 wherein each said pulse establishing circuit comprises a trigger element,

a storage element coupled to said trigger element for periodically triggering same until said storage element is discharged, and

a conduction disabling circuit connected to the output of said triggering element for periodically disabling same.

39. Apparatus according to claim 38 wherein a delay element is interposed between said counter and said second group of inputs. and

said delay element has an output connected to said storage element.

40. Apparatus according to claim 38 wherein the relative parameters of said storage element and said conduction disabling circuit determine the number of times said triggering element can be triggered while said storage element is being discharged, and each said triggering provides one of said correction pulses to said feedback path.

41. Apparatus according to claim 40 wherein said counter comprises a plurality of serially coupled counting stages each designating a numeric order, and said apparatus further comprises pulse synchronized interrogating circuitry connected to at least the numerically most significant of said stages for obtaining their count value for readout purposes.

42. Apparatus according to claim 41 in which said data pulses are each derived from a particle in a fluid suspension. and said apparatus further comprises regulating means responsive to the measurement of a predetermined volume of the fluid suspension, for purposes of particle analysis, to thereby regulate the duration of the operation of said correction pulse generator. 

1. A method for progressively and automatically correcting the digitalized accumulation of counting data which normally is subject to random error, comprising the steps of: receiving in a cumulative and digitalized mode the counting data as an augend, detecting in a cumulative and digitalized mode the value of the augend relative to a succession of addend corrections and instances of correction, such instances of correction being correlated to a predetermined set of augend values, determining the succession of addend corrections for each value in the set of augend values, generating the correlated addend at each instance of correction, and applying to the augend each addend as it is generated, such that the augend cumulatively is the sum of the counting data and the addends.
 2. A method according to claim 1 further comprising the step of relating the amount of addend, for said generating and applying steps, to the then detected valuE of the augend.
 3. A method according to claim 2 further comprising the step of enabling said generating of at least some of the addends at a prior instant related to the detecting of certain augend values.
 4. A method according to claim 2 further comprising repeating said generating at fixed values of the augend which are digitally spaced primarily equally from one another.
 5. A method according to claim 1 further comprising the step of delaying in a predetermined mode said generating relative to said detecting for an interval based upon the receipt of a fixed increment of augend.
 6. A method according to claim 1 further comprising creating by said generating different individual amounts of addend, depending upon the then received value of the augend.
 7. A method according to claim 6 further comprising producing by said generating, for said applying, at least one pulsed response, each such pulsed response being a fraction of the addend thereby applied.
 8. A method according to claim 6 further comprising creating by said generating addends which are multiples of one another depending upon the value of the augend.
 9. A method according to claim 1 further comprising the step of correlating the addend of each correction individually and cumulatively with a theoretical statistic correction curve.
 10. A method according to claim 1 and accomplishing said receiving and detecting by arranging in digital order a plurality of count retaining stages and directing said applying, at said instances of correction, to a particular one of the ordered stages depending upon the amount of addend and the value of the augend.
 11. A method according to claim 10 further comprising the step of obtaining from at least some of the ordered stages, as a representation of the results of the receiving and applying steps, the corrected count they are retaining.
 12. A method according to claim 11 further comprising interrogating sequentially each of the stages for the count it is retaining, during said obtaining.
 13. A method according to claim 1 further comprising the step of initiating the counting data in an analyzer of particles.
 14. A method according to claim 13 further comprising the steps of moving a fluid suspension of particles for purposes of said initiating, and regulating said generating and applying with reference to said moving.
 15. A method according to claim 14 further comprising sensing individual particles in suspension as they pass with reference to a scanning zone, for purposes of said initiating, the random error being caused by the physical coincidence of particles in the scanning zone.
 16. Apparatus for progressively and automatically correcting the digitalized accumulation of counting data which normally is subject to random error, comprising: means for receiving in a cumulative and digitalized mode the counting data as an augend, means coupled with said receiving means for detecting in a cumulative and digitalized mode the value of the augend relative to a succession of addend corrections and instances of correction, such instances of correction being correlated to a predetermined set of augend values, means for determining the succession of addend corrections for each value in the set of augend values, means responsive to at least said determining means for generating the correlated addend at each instance of correction, and means for applying to the receiving means each addend as it is generated, such that the augend cumulatively is the sum of the counting data and the addends.
 17. Apparatus according to claim 16 further comprising control means coupled to said generating means for relating the amount of addend next to be generated to the then detected value of the augend.
 18. Apparatus according to claim 17 further comprising means responsive to at least said receiving means for enabLing said generating means, for at least some of the addends, at a prior instant related to the detecting of certain augend values.
 19. Apparatus according to claim 17 wherein said detecting and control means, in combination, form means for triggering said generating means at fixed values of the augend which are digitally spaced primarily equally from one another.
 20. Apparatus according to claim 17 wherein said detecting and control means are arranged to coact to correlate the addend of each correction individually and cumulatively with a theoretical statistic correction curve.
 21. Apparatus according to claim 16 further comprising means interposed between said detecting and generating means for delaying in a predetermined mode the operation of said generating means for an interval based upon the receipt by said receiving means of a fixed increment of augend.
 22. Apparatus according to claim 16 wherein said generating means includes means for defining different individual amounts of addend, depending upon the then received value of the augend.
 23. Apparatus according to claim 22 wherein said defining means includes means for applying at least one pulsed response to the augend value, such that each pulsed response is a fraction of the addend thereby applied.
 24. Apparatus according to claim 22 wherein said defining means includes means for creating addends which are multiples of one another depending upon the value of the augend.
 25. Apparatus according to claim 16 wherein a plurality of digitally ordered count retaining stages comprise said receiving means and at said instances of correction, said applying means is selectively coupled to a particular one of the ordered stages depending upon the amount of addend and the value of the augend.
 26. Apparatus according to claim 25 further comprising means for obtaining, from at least some of the ordered stages, the corrected count they are retaining.
 27. Apparatus according to claim 26 wherein said obtaining means includes means for interrogating sequentially each of the stages for the count it is retaining.
 28. Apparatus according to claim 16 further comprising means for initiating the counting data in an analyzer of particles.
 29. Apparatus according to claim 28 wherein said initiating means comprises means for moving a fluid suspension of particles and means for regulating said generating and applying means in response to the amount of suspension moved by said moving means.
 30. Apparatus according to claim 29 wherein said initiating means further comprises means for sensing individual particles in suspension as they pass with reference to a scanning zone, the random error being caused by the physical coincidence of particles in the scanning zone.
 31. Apparatus for automatically and progressively applying a digitalized statistic correction to a progessive accumulation of data which is transmitted in the form of a train of data pulses that is subject to random error due to the mode of transmitting such data, said error following a statistically preascertainable course, said apparatus comprising: a counter having an input for receiving the data pulses and a plurality of outputs responsive to and designative of different data pulse count values, a correction pulse generator having a plurality of inputs connected to said plurality of outputs and arranged to be selectively responsive to said outputs for generating correction pulses at different of said count values, at least one feedback path coupling said correction pulse generator to said counter and arranged for progressively applying thereto correction pulses having a count value and progression occurrence so as to closely follow the preascertainable course of said error, so as to offset same.
 32. Apparatus according to claim 31 wherein said correction pulse generator comprises at least one control circuit having a first grOup of said plurality of inputs, and at least one pulse establishing circuit, coupled to be enabled by said control circuit, and having a second group of said plurality of inputs.
 33. Apparatus according to claim 32 wherein each pulse establishing circuit is coupled to supply correction pulses to said feedback path, and said feedback path is coupled to said counter such that each correction pulse is the equivalent to a specific multiplicity of count pulses, dependent upon the count value.
 34. Apparatus according to claim 32 wherein said plurality of inputs includes a third group coupled to specific ones of said control circuits and arranged to enable them at different specific count values.
 35. Apparatus according to claim 32 wherein a plurality of coupled pairs, each having one of said control circuits and one of said pulse-establishing circuits, is provided, each said circuit pair has one of said first and second groups of inputs, and each said circuit pair is responsive to a selectively different range of count values.
 36. Apparatus according to claim 35 wherein circuitry means intercouples said circuit pairs in such manner that only one pair is capable of responding to the counter outputs at any one time, and such capability correlates to the selectively different range of each said circuit pair.
 37. Apparatus according to claim 36 wherein a first power source, which is arranged to have enough power to operate only one of said control circuits at any one time, is intercoupled to said control circuits and comprises said circuitry means, and said first group of inputs are selectively connected to the control circuits to determine their sequence of operation.
 38. Apparatus according to claim 32 wherein each said pulse establishing circuit comprises a trigger element, a storage element coupled to said trigger element for periodically triggering same until said storage element is discharged, and a conduction disabling circuit connected to the output of said triggering element for periodically disabling same.
 39. Apparatus according to claim 38 wherein a delay element is interposed between said counter and said second group of inputs, and said delay element has an output connected to said storage element.
 40. Apparatus according to claim 38 wherein the relative parameters of said storage element and said conduction disabling circuit determine the number of times said triggering element can be triggered while said storage element is being discharged, and each said triggering provides one of said correction pulses to said feedback path.
 41. Apparatus according to claim 40 wherein said counter comprises a plurality of serially coupled counting stages each designating a numeric order, and said apparatus further comprises pulse synchronized interrogating circuitry connected to at least the numerically most significant of said stages for obtaining their count value for readout purposes.
 42. Apparatus according to claim 41 in which said data pulses are each derived from a particle in a fluid suspension, and said apparatus further comprises regulating means responsive to the measurement of a predetermined volume of the fluid suspension, for purposes of particle analysis, to thereby regulate the duration of the operation of said correction pulse generator. 